Optical spectroscopic and photometric classification of the X-ray transient EP240309a (EP J115415.8-501810) as an intermediate polar

2024/05/03 by S. Potter, D. A. H. Buckley, Potter, Stephen. B. +29
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astrophysical Phenomena and Observations #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)

paper · pdf · doi:10.48550/arxiv.2405.01996

openalex publication_date 2024/05/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We report on optical follow-up observations of an X-ray source initially detected by the Einstein Probe mission. Our investigations categorize the source as an intermediate polar, a class of magnetic cataclysmic variables, exhibiting an orbital period of 3.7614(4) hours and a white dwarf spin period of 3.97 minutes. The orbital period was identified through TESS observations, while our high-speed photometric data, obtained using the 1.9m and Lesedi 1.0m telescopes at the South African Astronomical Observatory, revealed both the spin and beat periods. Additionally, we present orbitally phase-resolved spectroscopic observations using the 1.9m telescope, specifically centered on the Hbeta emission line, which reveal two emission components that exhibit Doppler variations throughout the orbital cycle.

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